Selector switch interlock circuits



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United States Patent O 3,188,525 SELECTQR SWITCH INTERLOCK CIRCUITS Douglas W, Fath, Brookfield, Theodore 'Kraschinsky, .lr.,

lvlilwaukee, and Gene '0. Lutsch, Hales Corners,'Wis.,

assignors to CutlerHammenInc, Milwzurlree, Wis., a

corporation of Delaware Filed Mar. 15, 19.61, Ser. No. 96,024

10 Claims. (Cl. 317-135) This invention relates to .position locking selector switches and control therefor.

In control systems utilizing a plurality of electrical selector switches to provide different modes of apparatus operation, electrical. interlocking is often provided. 'This is done to either requirea certain sequence of selector switch operation, or. to prevent inadvertent change in mode of apparatus operation :until .a predetermined positioning of one or more, .or all of the selector switches is effected. Most commonly such interlocking employs electroresponsive relays which function to electrically disconnect some or all of the commutating contacts of a selector switch to render them ineffective. Effectiveness of the interlocking depends upon theproper operation of such relays and the circuitry thereof often involves proper sequential operation of auxiliary contacts of electromagnetic contactors and other relays. In interlocking employing such relays, the circuitry in many cases is such that they will not automatically reoperate to provide interlock protection following power failure and reestablishment, thereby requiring operator resetting of the circuits involved to insure that interlock protection is afforded.

It is a primary object of the present invention to provide improved forms of interlocking for electrical selector switches wherein such a switch, or switches, are locked in or out of certain operating positions thereby providing direct indication to the operator, because of inability to operate the same from or into such positions.

Another object is to provide interlocking of the aforementioned type which is directly controlled by the predetermined positioning of the selector switches themselves without need for use of auxiliary relays or the like. A further object is to provide interlocking of the aforementioned character which is self returning following power failure and reestablishment.

A more specific object is to provide selector switch interlocking control which is directed by commutation of contacts operated directly-by the selector switches involved.

Other objects and advantages will hereinafter appear.

In the drawing:

FIGURE 1 is a more or less schematicshowing in side elevation of a rotary, shaft operated multi-position selector switch incorporating position locking means;

FIG. 2 is a view taken along the line. 2-2 of FIG. 1;

FIG. 3 is a diagrammatic and schematic view of an interlocking control system for a plurality of position locking selector switches;

FIG. 4 is a another view like FIG. 3, but showing an interlock control system for two, three-positions and one two-position selector switches; and

FIG. 5 is another view like FIG. 4, but showing a modified form of interlocking control system for such selector switches.

Referring to FIG. 1, it shows a rotary shaft operated manual selector switch having a frame 10, comprising a plate 11, shaft and switch supporting brackets 12 and 13, and'solenoid supporting bracket 14. An operating shaft 15 is afforded rotatable bearing supported in, and constrained against axial movement in the brackets 12 and 13. A conventional manual operators handle 16 is non- 3,188,525 Patented June 8 1965 rotatably secured to the end of shaft 15 which projects beyond bracket 12.

.The shaft 15 may be assumed to be rotatable through movement of handle 16 to two or more definite rotary spaced. operating positions wherein itis adapted to commutate a plurality of electrical switches, schematically depicted at 17 which may be assumed to be of conventional type (not shown). vFor example, in one preferred form they may be like that shown in Patent No. 2,521,519 having movable contact operating plungers operated by cams "non-rotatably mounted on shaft ,15. Similarly, a conventional position indexing means (not shown) would be employed to define the definite rotary operating positions for shaft .15.

A circular disc 18 isnon-rotatably securedto the end of shaft 15 which projects to the left beyond bracket 13. As shown in FIGS. 1 and 2, cylindrical pins comprising a first group designated 19, 2.0 and .21 and a second group, designated 22, 23 and-24, spaced at the .same radial distance from the center of disc, but apart fom each other, are secured to disc 18. Electromagnetic solenoid assemblies 25 and 26, are mounted on bracket14 so. that the axes of their plungersfZSa and 26a lie directly opposite each other on a-straight line running through the center of disc 18 and in line respectively, with pins of the first group 19, 20 and 21 and pins of'thesecond group 22, 23 and 24. Solenoid assemblies 25 and 26 have energizing coils 25b and 2611 which are selectivelyenergizable to withdraw their plungers 25a and 26a out of .the paths of the groups ofpins 19-21 and 22:24 against the bias of return springs.

The rotary direction arrows and legends shown in FIG. 2 correspond to those obtained by the designated movement of handle 16 when looking in the right side of bracket 12 in'FIG. 1. Now,if it be assumed that solenoid coil 25b is deenergized permitting-its plungers 25a to be dropped into the path of .pin 19, rotation of operating shaft 15 in the counterclockwise direction to another operatingposition will be prevented. Likewise, if coil 26b of solenoid 26 is deenergized its plunger 26a will be biased into the path of pin 24 thereby preventing clockwise rotation of operating shaft'15. If coil 25b is energized and coil 26b remains deenergized the retraction of plunger'25qwill permit rotation of shaftlS in the counterclockwise direction, but as plunger -26 a remains in interferring relation to pin 24, shaft 15 cannotbe rotated ,in the clockwise direction. It will be apparent that with coil 26b-energized and coil;25b deenergized that shaft 15 can then'be rotated in the clockwise direction but not in the counterclockwise direction. When both solenoid coils 25b and 26b are energized shaft 15 can, of course, be rotated freely in either the clockwise or counterclockwise directions.

-Let it beqassumed that -with.disc.18 in the position shown in'FI G. 2, shaftt15 will have a corresponding position providing off operating condition .of the switches operated thereby. Now if coil 26b is energized retracting plunger 26a, shaftlS may then be assumed to be operable to. a definite rotary operating position in the clockwise direction .wherevcertain switches controlled by shaft ;15 may beassumed to be operated to closed circuit condition. Similarly, if coil 25b .is energized affording retraction of plunger 25:: shaft 15 may then be assumed to be operable to a definite operating position in the counterclockwise directionwherein other switches rolledby shaftlSm-ay be assumedrto be operated to -closed-circuit condition. It. will be seen that after shaft 15 has been rotated to its clockwise operating position, if, coil 26b is deenergized to cause plunger 26a to be moved into the pathof .pin'=22 (dotted line position thereof)- shaft cannot be rotated back to off position. Like- The diagram in the left-hand portion of area,

Q wise, shaft '15 cannot be rotated from its counterclockwise operating position back to off if coil 25b is deenergized permitting plunger 25a to be moved into interfering relation to pin 21 (dotted line position).

If desired, one of the solenoid locking assemblies shown in FIGS. 1 and 2 can be omitted thereby affording locking against rotation of shaft from off to only one of its other two operating positions, or locking it against return to off from the last mentioned operating position. It will also be apparent that the application ofthe solenoid locking feature can be applied to rotary shaft operated switches having any number of definite operating positions; solenoid locking assemblies being added and.

positioned in accordance with the locking pattern desired.

While only two pins are actually needed in each solenoid locking assembly shown in FIG. 2, pins 19 and 21 or 22 and 24,the middle pins or 2.? are added to prevent accidental engagement of the solenoid plungers between 19 and 21, or 22 and 24 when the shaft is in transition between oh and one of its other two operating positions. If desired, the sets of pins could be replaced by 'solid segments spanning the same arcuate distance. The

use of pins make for easy assembly and location in the disc 18.

7 FIGS. 3, 4 and 5 disclose examples of types of interlock circuits that can be used to advantage with two or more rotary shaft selector switches which embody the locking solenoid arrangements aforedescribed in conjunction with FIGS. land 2. r

FIG. 3 shows an interlocking circuit for two, three-position selector switches A and B. As shown in the right-hand portion of FIG. 3 switches A and B have solenoid plungers ALSP and BLSP which cooperatewith disc pin ADPI- ADPZ and BDPLBDPZ, respectively, to provide locking as hereinafter described. As shown inthe circuit diagram of FIG. 3, contacts B1 of switch B are connected across voltage supply lines L1 and L2 in series with the solenoid coil of switch A, and contacts A1 of which A are similarly connected in series with coil ALS and in parallelwith contacts B1. Contacts A2 of switch A are'connected in series with coil BLS of the locking solenoid of switch B across lines L1 and L2, and the contacts B2 of the latter switch are similarly connected in series with coil BLS, and in parallel with contacts A2.

The operating positions of the interlock in the circuit diagram is that occurring when switches A contacts shown,

erated to set the latterin motion so there is no interruption of continuity of material supply to the processing line. Similarly such arrangement can be used to insure that a standby electrical generator is connected to a load be-v fore another previously supplying the load is disconnected therefrom. V

The circuit diagram in the left-hand portion of FIG. 4

' shows aninterlock circuit for two, three-position selector switches C and D having the locking solenoids of our invention, and a two-position, non-locking selector switch E. As shown in the right-hand portion of FIG. 4, switches C and D have solenoid plungers which cooperate with disc pins CDPl-CDPZ and DDPl-DDP2, respectively, to provide position locking as hereinafter described. Asshownin the circuit diagram contacts D1 of switch D are connected in series with locking solenoid coil CLS of switch C across lines L1 and L2, and contacts E1 of switch E are similarly connected in series with coil CLS and in parallel with contacts D1. Contacts Cl and B areboth in center oflf position. As the contacts Al and B2 areclosed coils ALS and BLS will both be energized to retract plungers ALSP and BLSP out of inter'fering relation with the pins ADP1-ADP2 and BDPl- BDPZ. Thus either of the switches A and B can be operated to their respective No. 1 positions. If switch A is operated to No. 1 position, then due to opening of contacts A1 when it reaches such position coil ALS will be deenergized to allow plunger ALSP to drop behind pin ADP2 and thereby lock switch A against return to off position. If switch B is thereafter operated to its No. 1 position closure of contacts B1 thereof reestablishes an energizing circuit of coil ALS to retract plunger of switch C are correspondingly connected in series with locking solenoid coil DLS of switch D across lines L1 and L2, and contact E2 of switch E are similarly connected in series with coil DLS and in parallel with contacts C1.

The operating condition of the switch interlocking contacts shown in the circuit of FIG. 4- is that occurring when both switches C and D are in their center oft positions and switch E is in AUTO position. As contacts DI and CI are both closed the coils CLS and DLS of.

switches C and D wil-lboth be energized, and thus either 7 of the latter can .be operated to its No. 1 position. Assume that switch C is then operated to its No. 1 position. In so doing, contacts C1 will open, thereby deenergizing coil DLS which results in plunger DLSP dropping into the'path of pin DDPl. Accordingly, op-

eration of switch D to its No. l position will be prevented so long as switch C remains in its No. 1'position. It will be seen .that if instead of switch D is first:

operated to its No. 1 position that operation 'of switch the apparatus in motion, overriding operation by manipu lation of a corresponding selector switch at another sta-' tion or stations is to be prevented. However, under other conditions it may be desirable to have overriding operation available at any station. Switch E in MAN position permits'overriding cont-r01 action'by an corresponding selector switch, while AUTO positioning of I switch E prevents overriding action. .It will be apparent ALSP so that switch A can then be returned to its ofi position as desired; It will be apparent that in a similar manner if switch B is first operated to its fNo. 1 position it will be locked'in such position until such time as switch A is operated to its No. 1 position. The'placement of pins ADPl-ADPZ and BDPl-BDPZ in-the discs 18in relation to plungers ALS? and BLSP is suchthat switches a A and'B have, unrestricted operation between their oif and No. 2 operating positions. I

The foregoing interlock arrangement for two selector switches is useful when each may be'used in No; 1 position to set in motion a source of supply of definite capacity to a continuous processingline. Thus, switch A controlling'one such source cannot be operated to shut it jdownuntil switch B controllinga second source is opclosed'contacts, i.e., C1 and Di, with each switch locking which'have locking solenoids.

that if additional selector switches like C and D are used in the system, additional contacts equal to the number of.

suchswitches could be connected in series with the off solenoid coil. a a 7 The diagram in the left-hand portion of FIG. S-shows an interlock circuit for two, three-position selector'switches 'F and G andone, two-positionaselector switch H, all of hand portion of FIG. 5, switches F and G have solenoid plungers FLSP and GLSP which cooperate with disc pins FDRl-Z and GDPl-Z and plunger .I-ILSP which cooperates with disc'pins HDPI-Z to provide locking as" hereinafter described. As 'shown in the circuit diagr'am contacts Glof switch are connect? ed in se-rieswith solenoid coil FLS of switch F across 7 lines Lland L2. Contacts F1 of switch F and contacts H1 As shown inthe rightswitch H has a solenoid are similarly connected in series with coil FLS and in parallel with each other and contacts Gl. Contacts P2 of switch F are connected in series with solenoid coil GLS of switch G across lines L1 and L2 and contacts G2 and H2 of switch G and H are similarly connected in series with coil GLS and in parallel with each other and contacts F2. Contacts F3 and G3 are connected in series with each other and solenoid coil HLS across lines L1 and L2, and contacts H3 are similarly connected in series with coil HLS, and in parallel with contacts F3 and G3.

The operating condition of the switch interlock contacts shown in the circuit of FIG. 5 isthat occurring when switches F and G are in their center off positions and switch H is in its left-hand AUTO position. As contacts F1, G2 and H3 are closed the solenoid coils FLS, GLS and HLS will be all energized permitting movement of switches F and G to their respective No. 1 positions and movement of switch H to its MAN position. Assume that either one of the switches F and G is first operated to its No. 1 position. It will be seen that the first one so operated will be locked in No. 1 position and will not be operable back to off until the other thereof is first operated to its No. 1 position as aforedescribed in conjunction with FIG, 3. Assume that switch H is operated to MAN position. Thus, unless switches F and G are both in their No. 2 positions, switch H will be locked in its MAN position, With switch H in MAN position either or both of the switches can be operated to any of their positions without lock-ing.

It will be seen that the arrangement of FIG. 5 is useful when a control system can either be set for an automatic sequential operation or for manual operation requiring individual operation. The system cannot be changed to automatic operation unless both the threeposition selector switches are in the same operating positions. The interlock as between the two, three-position selector switches F and G is of course, the same as that aforedescribed in conjunction with FIG. 3 and has the virtues hereinbefore described.

We claim:

'1. In combination, a plurality of selector switches each of which comprises an opera-ting shaft rotatable between at least two definite angularly spaced operating positions, a stop member carried by said shaft and an electromagnetic device having an operating coil and plunger biased into interferring relation with said stop member when said coil is deenergized and retractable therefrom when said coil is energized, and electrical control means for the operating coils of said devices including and being under the direction of switch contacts of said selector switches and affording when the operating shafts of the latter are in predetermined positions deenergization of the coil of the electromagnetic device of one of said selector switches to prevent its operating shaft from being operated in another operating position.

2. The combination according to claim 1, wherein said electrical control means is responsive to movement of the operating shaft of any one selector switch to one rotary position to deenergize its electromagnetic device to lock such switch in said one rotary position and wherein said control means is responsive to following movement of the operating shaft of a second selector switch to said one rotary position to energize the electromagnetic device of said any one of said selector switches.

3. The combination according to claim 2, wherein the movement of the operating shaft of any one only of said selector switches to said one rotary position opens contacts carried thereby to deenergize the operating coil of its electromagnetic device, and wherein following movement of the operating shaft of another of said selector switches to said one rotary position closes contacts carried thereby to reenergize the operating coil of the electromagnetic device of said any one only of said selector switches.

4. The combination according to claim 1, wherein said control means is responsive to movement of the operating shaft of any one selector switch to one rotary position to deenergize the electromagnetic device of another selector switch to prevent the movement of the operating shaft of the latter to said one rotary position while the operating shaft of the former is in that position.

5. The combination according to claim 4, wherein the movement of the operating shaft of the first mentioned selector switch to said one rotary position opens contacts carried thereby to deenergize the operating coil of the electromagnetic device of said other selector switch.

6. The combination according to claim 4, together with a non-locking selector switch operable to a given position to continuously energize the electromagnetic devices of all the electromagnetic devices of the first mentioned selector switches and operable to another given position to permit the interlocking action aforestated.

7. The combination according to claim 6, wherein the movement of the operating shaft of the first mentioned selector switch to said one rotary position opens contacts carried thereby to deenergize the operating coil of the electromagnetic device of said other selector switch, and wherein said non-locking selector switch when its operating shaft is in said given position closes contacts carried thereby to energize the operating coils of said first and said other selector switch.

8. The combination according to claim 1, wherein said control means is responsive to movement of the operating shafts of two of said selector switches to given corresponding positions, and movement of the operating shaft of a third selector switch to a predetermined position to deenergize the electromagnetic device of the latter to lock the shaft of the latter in such position, wherein movement of both operating shafts of said two selector switches to second corresponding positions renders said control means effective to energize the electromagnetic device of said third selector switch when its operating shaft is in said predetermined position.

9. The combination according to claim 8, wherein when the operating shafts of said two selector switches are in said given'corresponding positions and the operating shaft of said third selector switch is in a second predetermined position said control means is responsive upon following movement of the operating shaft of either of said two selector switches to said second corresponding position to deenergize its electromagnetic device to lock its shaft in such position, and wherein further following movement of the operating shaft of the other of said two selector switches to said second corresponding position energizes the electromagnetic device of the first of said two selector switches.

14). The combination according to claim 8, wherein movement of the operating shaft of said two selector switches to said given corresponding position closes contacts individual thereto and connected together in series with the operating coil of the electromagnetic device of said third selector switch to complete an energizing circuit for the latter, and wherein when the operating shaft of said third selector switch is in said predetermined position it closes contacts in circuit with each of the operating coils of the electromagnetic device of each of said two selector switches to complete energizing circuits for both thereof.

References Cited by the Examiner UNITED STATES PATENTS 1,454,526 5/23 Turner 307-142X 2,719,927 10/55 Courtney 317136 SAMUEL BERNSTEIN, Primary Examiner. WALTER L. CARLSON, Examiner. 

1. IN COMBINATION, A PLURALITY OF SELECTOR SWITCHES EACH OF WHICH COMPRISES AN OPERATING SHAFT ROTATABLE BETWEEN AT LEAST TWO DEFINITE ANGULARLY SPACED OPERATING POSITIONS, A STOP MEMBER CARRIED BY SAID SHAFT AND AN ELECTROMAGNETIC DEVICE HAVING AN OPERATING COIL AND PLUNGER BIASED INTO INTERFERRING RELATION WITH SAID STOP MEMBER WHEN SAID COIL IS DEENERGIZED AND RETRACTABLE THEREFROM WHEN SAID COIL IS ENERGIZED, AND ELECTRICAL CONTROL MEANS FOR THE OPERATING COILS OF SAID DEVICES INCLUDING AND BEING UNDER THE DIRECTION OF SWITCH CONTACTS OF SAID SELECTOR SWITCHES AND AFFORDING WHEN THE OPERATING SHAFTS OF THE LATTER ARE IN PREDETERMINED POSITIONS DEENERGIZATION OF THE COIL OF THE ELECTROMAGNETIC DEVICE OF ONE OF SAID SELECTOR SWITCHES TO PREVENT ITS OPERATING SHAFT FROM BEING OPERATED IN ANOTHER OPERATING POSITION. 